Binder for peroxid active material and process of making it.



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pound of sures rarsnr QF a e. a 'J fl ck. .fihaoxm i la'rnam raojcnss or; m

110 Drawing.

To all whom it may concern:

Be it known that I, WVILLIAM Mona-1501s, a citizen of the United States, residing at Des Moines, in the county of Folk and State of Iowa, have invented certain new and useful Improvements in Binders for Peroxid Active Material and Processes of Making Them, of which the following is a specification.

This invention relates to the production of a permanent and insoluble binder for the active material of the positive-pole electrodes of lead storage batteries. This binder fundamentally comprises an oxygen-com,- a metal incapable of directly replacing hydrogen in a sulfuric acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separa tion as metal, in a sulfuric acid solution; and capable of forming complex'anions with electronegative elements, which can consti tute the acidic radical of com ounds having lead as a base. The three nown metals which have these characteristics are tungtantalum, and niobium, otherwise called columbium.

.To illustrate the invention, there will first be described an electrolytic process of pro* doping 3. lead-peroxid electrode employing of tungsten as the binder. For this purpose, a metallic support, for example .a grld of antimonial lead, is pasted' or filled with the usual mixture ofminium, litharge and a sulfuric acid solution, in which mixture lead sulfate forms as a provisional binder. Complete formation, or peroxida' tion, of the active material is then preferably initially effected by placing the pasted grids, alternately with unfilled grids servmg as dummy electrodes of the opposite polarity, in a sulfuric acid solution having a specific gravity of 1.200 to 1.250 and pass ing an electric current through the solution, alternately in opposite directions, until the paste has been sufiiciently expanded,./care being taken not to force the discharge beyond the normal intended capacity of the electrodes. The formed and dummy electrodes are then removed from the sulfuric acid solution and placed in a cell containing water, 'and'electric current is passed from the filled electrodes to the dummies until the free acid in the active material has been removed. The electrodes and dummies are then removed, rinsed in water, and placed a compound of Application filed February 20,1912. Serial No. 679,171.

ions,

ence p tinteil h'priz, 191s.

in a strong aqueous solution of an. alkalimetal tungstate, for example sodium para} tungstate. An electric currentis then.v from the filled electrodes through for several hours, thereby causing tungsten presumably complex tungsten oxygen ions, to penetrate the active material many desired de ree and to combine chemically with the cad-oxygen compounds thereof, and particularly serves as the provisional binder mime trode. The electrodes and dummies arethn removed, rinsed in water, placed in a sulfuric acid solution having a specific gravity of about 1.300, and an electric current is passed from the electrodes to the dummies until all of the soluble constituentsv of the 'active material have been removed or.,'1 "e x 1- dered insoluble. B

hydrated tungstic sal t insoluble or non-hydrous condition. It ism this insoluble state that the tungsten coin pound serves as an efiicient and inertbinddr. The electrodes are then dischargedto the extent of their normal capacity, andthe'r es after recharged, preferably to somewhat less than their full capacity, in anothersulfujgic acid solution of 1.280 specific gravity; the effect of such incomplete recharging leave in the plate a certain proportion "of; lead; sulfate to combine with the tungsten ions on a repetition of the treatment,'s hould such repetition be desired, for the purpose of impregnating the active materialflvvith an additional the positive-pole electrodes are mounts "1m connection with the regular negative'platj'es, and receive their full normal charge.

The object of performing thepreeedin The tungsten-oxygen anion play the same role in the binder c m as as does the sulfunoxygen anionfin the Iiifdl nary lead electrodes in which l' nd Sulfate constitutes the binder, Th l ding a g oxygen compound is however, as

'li solution to the dummies, and is continued with thelead sulfatewhich amount of the binderi eoingt pound. At the conclusion of the treatment this treatment any is converted into the, a

,salt, aslead nitrate or acetate;

' m'ore, is very. inu'nnm-litharge paste,

with the lead sulfate heretofore commonly used as a binder, very permanent and insoluble, bein chemically and electrochemically inert un er the conditions of use, while acting as an eflicient binder. This binder, by reason of its inactivity, som'ewhat decreases the capacity of the electrodes, to the same extent that it displaces or occupies the place of lead peroxid. The initial formation of the electrodes may be omitted and the filled grids may be at once placed in the tungstate solution to im regnate the active material with the bin er, formation being subsequently 'eflected. Such subsequent formation, however, consumes much larger amount of current than does initial formation..

While the described electrolytic process of impregnation-is an eflici ent and operative one, i is sometimes preferable, particularly with thick plates, in order uniformly to distribute the binder throughout the active mass, to incorporate a. portion of the binder with" the active material by other methods, two of which will now be described. The first of these optional methods consistsin forming an aqueous solution of asuitable lead adding so dium paratungstate until all the lead is precipitated, separating the recipitate and washing it with dilute sul ric acid, then boiling it in strong sulfuric acid, washing it with water, and heating it nearly or quite to'its meltingpoint, in order to give it a 'd'enser body. The desired proportion of this product, say from six to ten per cent. or thoroughly-mixed with the p as by grinding the materials together. The active material so prepared is then applied to the grid. The second of these optional methods consists in dissolving the desired amount of sodium paratun state in a ten 'yplume aqueous solution of ydro en peroxid, that is to say a 1 solution capab e of liberating ten volumes of oxygen, and then addin slowly and with constant stirring a sul .uric acid solution having a specific gravity of 1.200 to 1.225 until efli'ervescence ceases. There is then added an additional and preferably an equal amount of said sulfuric acid solution, and the formed positive electrode is dipped in the solution, then removed and permitted to dry with exposure to air, and again dipped and dried one or more times as may be desired.

One effect ofthe hydrogen pcroxicl as above used is to prevent precipitation of tungstic acid upon the addition of the sulfuric acid; and if any tendency to such precipitation is observed, more hydrogen peroxid should be added until the solution remains clear. lhe hydrogen peroxid is used in some excess, and serves also in presence of the sulfuric acid to reduce the lead pcroxid of the formed electrode, and thereby to facilitate the ultimate production of the lead-tungsten-oxygen binder. If stronger hydrogen peroxid solutions are used a correspondingly smaller volume will be required.

The positive-pole electrode prepared by eitherof the above described optional methods should receive a prolonged and stron charging treatment in sulfuric acid, with dummy negatives, before assembling in the battery, in order to remove or to render insoluble any remaining soluble components of the plate.

The foregoing methods may be used singly or in cpinbinati n as desired, but if used in combination it is preferred to use the electrolytic method first above described as the finishing stage.

It is to be foregoing examples are illustrative in character, and that the invention is not limited to the details of manipulation or to the strength or proportions of reagents recited; and it is also to be understood that the positivepole electrodes. may be prepared by methods other than those herein specifically described without departure from my invention.

Positive-pole electrodes having a binder containing tantalum or niobium may be prepared by either or both of the first and second methods above described, a soluble tantalate or niobate, as for example potassium hexatantalate or niobate, being used either as an electrolyte in the first method, or as a precipitant for the lead salt in accord ance with the second method. The active material of Plant electrodes, formed out of solid lead, may also be bound by using either the first or third of the above-do scribed methods, that is by employing them as anodes in a solution of a tungstate, tantalate or niobate, or by dipping them in a hydrogen peroxid solution of a salt of the binder'meta'l, and then completing the treatment as before.

I claim:

1. Apermanent binder for the active material of positive-pole lead electrodes, consisting of a compound having in its acidic radical a metal incapable of directly replacing hydrogen in a sulfuric acid solution; insoluble" by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anions with electro ncgative elements.

'2."A permanent binder for the active material of positive-pole lead electrodes, consisting of a lead compound having in its acidic radical a metal incapable of directly replacing hydrogen in a sulfuric acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separaunderstood that the several tion as metal, in a sulfuric acid solution; and capable of forming complex anions with electro-negative elements.

3. A ermanent binder for the active material o positive-pole lead electrodes, consisting of an oxygen compound of lead and a metal incapable of directly replacing hydrogen in a sulfuric acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming'complex anions with electroncgative elements.

4. A permanent binder for the active material of positive-pole lead electrodes, consist- -ing of an oxygen-sulfur compound of lead and a metal incapable of directly replacing hydrogen in a sulfuric-acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anions with electronegative elements.

5. A permanent binder for the active material of positive-pole lead electrodes, consisting of a compound having tungsten in its acidic radical.

6. A permanent binder for the active material of positive-pole lead electrodes, consisting of a lead compound having tungsten in its acidic radical. V v V 7. A permanent binder for the active material of positive-pole lead electrodes, consisting of an oxygen compound of lead and tungsten.

8. A permanent binder for the active material of positive-pole lead electrodes, consisting of an oxygen-sulfur compound of lead and tungsten.

9. In a process of binding the active material of positive-pole lead electrodes, the

step which consists in impregnating the active material with a compound containing in its acidic radical a metal incapable of directlyreplacing hydrogen in a sulfuric acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anions with electronegat-ive elements.

10. In a process of binding the actice material of positive-pole lead electrodes, the step which consists in electrolytically impregnating the active material with a com pound containing in its acidic radical a metal incapable of directly replacing hy-- .terial of positive-pole lead electrodes,

drogen in a sulfuric acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anions with electronegative elements.

11. In a process of binding the active material of positive-pole lead electrodes, the step which consists in impregnating the active material with a compound containing tungsten in its acidic radical.

. 12. In a process of binding the active material of positive-pole lead electrodes, the step which consists in electrolytically impregnating the active material with a compound containing tungsten in its acidic radical.

13. In a process of binding the active material of positiveole lead electrodes, the step which consists in passing an electric current from the electrode through a solution of a tungstate, thereby impregnating the active materlal with a tungsten compound.

14. The process of bindin the active material of positive-pole lead e ectrodes, which consists in passing an electric current from the electrode through a solution of a tungstate, thereby impregnating the active material with a tungsten compound, and thereafter reacting on said compound with sulfuric acid.

15. The process of binding the active mawhich consists in assing an electric current from the electro e through a solution of a tungstate, thereby impregnating the active material with a tungsten compound, and there after elec'trochemicall reacting on said compound with sulfuric acid.

16. The process of producing positivepole lead electrodes having active material containing a permanent binder, which consists in dissolving a tungstate in a hydrogen peroxid solution, adding sulfuric acid, submergingthe electrode in the solution, removing it and drying it, passingan electric current from the electrode, as anode, through a solution of a tungstate, thereby impregnating the active-material with a tungsten compound, and reacting on said compound with sulfuric acid.

In testimon whereof I ailix my signature in presence 0 two witnesses.

WILLIAM MORRISON.

4 Witnesses:

EUGENE A. BYBNEB, ETHEL DANIELS. 

